Diddy1
join:2003-07-19
Sidney, NE
| Current flowing in drain wire on Cat5
I have cat5 with a copper ground wire in it. I am picking up slight current in this ground wire. However, the ground wire is not utilized in this setup. At both ends, the ground wire is just bent back. I am not detecting any shorts in the cable either and POE is used here. So, could the ethernet transmission over the cable be inducing current into the groun wire? I feel a very slight tingle when touching it while standing on very wet ground/grass, been raining all night and day here. I have to press the wire into my skin to feel the tingle. The tower this equipment is on IS grounded with a 6' ground rod etc.
Aaron |
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SipSizzurp
Fo' Shizzle
Premium
join:2005-12-28
Hilo, HI
 ·RoadRunner Cable
| It is normal for a free floating piece of wire to pick up voltage from out of the air. It is very advisable to ground the drain wire at one end or the other, preferably NOT both ends unless it is a good earth ground at each end.
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Mi ultima pinche Carta Blanca. Que triste ! |
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slipstream1
Premium
join:2005-11-15
Jacksonville, TX | reply to Diddy1
If you ground it at both ends you will create a ground loop. That is bad. Ground it at the bottom end and the stray current will have a good path to ground. |
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Keithb
join:2003-09-16
US
| reply to Diddy1
We used shielded Cat 5 with static wire on our tower and left the top end ungrounded and grounded the lower end. I had to move the grounds once and noticed a little static. I think it will resonate from other cabling and the tower itself. I'm sure it just induces itself onto the wire. |
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Diddy1
join:2003-07-19
Sidney, NE
| reply to SipSizzurp
said by SipSizzurp  :It is normal for a free floating piece of wire to pick up voltage from out of the air. It is very advisable to ground the drain wire at one end or the other, preferably NOT both ends unless it is a good earth ground at each end. Would you say it is picking up current from the PtP setup on the tower now? I don't see how a wire just hanging in the air would produce any noticable potential difference.
Aaron |
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slipstream1
Premium
join:2005-11-15
Jacksonville, TX | reply to Diddy1
Anything that is not grounded will store static electricity from the atmosphere around it. |
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LLigetfa
join:2006-05-15
Fort Frances, ON
| What is generally referred to as *static* electricity is caused by friction, like petting the cat. Dry air moving through the atmosphere also causes static electricity as is evidenced by the bolts of lightning. I think you will find however, that the electricity induced into a long straight wire will be from electro-magnetic radiation. Static electricity requires some sort of collection plate and since the wire is insulated along its full length, there is not likely to be one.
Sorry for the knit-picking.  |
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SipSizzurp
Fo' Shizzle
Premium
join:2005-12-28
Hilo, HI
·RoadRunner Cable
| reply to Diddy1
said by Diddy1 :Would you say it is picking up current from the PtP setup on the tower now? The source of the voltage you feel is most likely from the signal on the cat5 itself. You can verify this by unplugging the cat5 cable at each end and see if it still shocks you. The longer the cable, the more induction the drain wire will get from the computer signals on the wire. Another big culprit of excessive free voltage in the air is high voltage power lines. They can radiate a significant amount of voltage for hundreds of feet, which your ungrounded cable will pick up like a transformer winding. Either way, your system will be much better off if you ground this wire. It was designed that way, to be grounded, which reduces the potential of data interference from spurious voltages.
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Mi ultima pinche Carta Blanca. Que triste ! |
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superdog
I Need A Drink
Premium,MVM
join:2001-07-13
Lebanon, PA
| What is everyone's opinion about using the drain wire for a ground lug on a radio??. Tranzeo for instance, has a ground lug on the back of the radio, and while I have never used it, the thought crossed my mind quite a few times, but I have never done it?.
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Diddy1
join:2003-07-19
Sidney, NE
| said by superdog :What is everyone's opinion about using the drain wire for a ground lug on a radio??. Tranzeo for instance, has a ground lug on the back of the radio, and while I have never used it, the thought crossed my mind quite a few times, but I have never done it?. I was wondering about this as well. On certain installations, it was always nice to know that if I needed to changed the grounding setup, there was another path already there for a potential ground connection. But, I have no idea either of the suitability.
Aaron |
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SipSizzurp
Fo' Shizzle
Premium
join:2005-12-28
Hilo, HI
·RoadRunner Cable
| reply to superdog
said by superdog :What is everyone's opinion about using the drain wire for a ground lug on a radio??. If the radio's case ground is tied to the electric ground of the power supply, you would need to watch out for ground loops. If the case ground does NOT connect to the power supply ground, you can ground it by any means with no worry of ground loops. The radio could easily be designed either way. A quick check with an ohm meter will give you the answer.
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Mi ultima pinche Carta Blanca. Que triste ! |
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Diddy1
join:2003-07-19
Sidney, NE | Ya, I'm very familiar with ground loops :P, but not to do with RF and wireless. I had an interesting experience with my home once on a wet rainy day and it has metal siding 
Aaron |
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Keithb
join:2003-09-16
US
| reply to superdog
So you would just attach the drain wire to the radio and leave the lower side un-attached to anything? Or physically use that for a ground?
I wouldn't use it for a ground as you will be inducing voltage on the line, and it's always best to use the shortest ground possible.
said by superdog :What is everyone's opinion about using the drain wire for a ground lug on a radio??. Tranzeo for instance, has a ground lug on the back of the radio, and while I have never used it, the thought crossed my mind quite a few times, but I have never done it?. |
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slipstream1
Premium
join:2005-11-15
Jacksonville, TX | reply to Diddy1
Using the drain wire to ground the radio would be a bad idea, I think. The ground would be almost the same length as the data and POE runs and the drain wire is not large enough to provide a good path to ground. |
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